Electrical control for a hydraulic elevator system



Feb. 2o, 1968 ELECTRICAL CONTROL FIOR A HYDRAULIC ELEVATOR SYSTEM 'R. F.MARTIN Filed April 8, 1964 ...l-Psw Nc I I l I Il u | I I I .1 I I I00h/N HLA CFLL/ oook OPER/772W? U ooo@ OPER/170A? MOTOR l?? @Qi/fifa@United States Patent Ofi-ice 3,369,633 Patented Feb. 20, 1968 3,369,633ELECTRICAL CONTROL FOR A HYDRAULIC ELEVATQR SYSTEM Richard F. Martin,Rock Island, Ill., assignor to Montgomery Elevator Company, acorporation of Delaware Filed Apr. 8, 1964, Ser. No. 358,201 9 Claims.(Cl. IS7- 29) 'ABSTRACT 0F THE DISCLOSURE A hydraulic elevator controlcircuit that includes a protective timer which is started each time themotor and pump start, and which has a cycle slightly greater than thetime required Afor the elevator to make a single trip from the bottomterminal to the top terminal without intermediate stops. If the timercycle is completed before the car stops at the top terminal the motor isstopped and the valves are operated to lower the car to the bottomterminal.

Hydraulic elevators have come into widespread use in recent years forrelatively fast passenger service in buildings having two to fourfloors. Modern installations require relatively high rates of fluid flowto produce the required high speeds, and this in turn increases thecomplexity of the valves required to control the movement of theelevator, and in particular to provide a smooth slow down at a floor andaccurate stopping at the floor level.

The more sophisticated modern'hydraulic elevator systems have caused anincrease in the possibility that a car will stall during upward travelwhen it is in the leveling zone .and traveling at a very low speed whichis commonly between 3 and 10 feet per minute. The reason is clear whenit is recognized that a hydraulic elevator uses a constant speed,constant displacement pump, so the reduction in elevator speed fromnormal running speed to leveling speed must be accomplished by partiallyopening a bypass valve that permits a predetermined portion of thehydraulic fluid to be bypassed back to the reservoir, so that only asmall fraction of the full flow is used to elevate the car at a slowrate for accurate leveling. Accordingly, in the leveling zone a changein viscosity of the oil, a lchange in valve characteristics, or evenslight slippage of the belt between the electric drive motor and thepump may be sufficient to cause the car to stall in the leveling Zone. A

lThe consequences of stalling a car in the up leveling zone are not tooserious in a freight elevator, because the elevator operator canordinarily reach the door interlock of the floor which the car wasapproaching when it stalled, open the door and get out of the elevator,whereupon he can take the necessary steps to ycut out the elevatorcircuit and thus preventl damage to the motor, the pump or the valves.On the other hand, in a passenger elevator with automatic doors whichcan open only when the elevator is stopped .at floor level, andparticularly in automatic passenger operated elevators, if a car stallsin the up leveling zone it can cause panic among the passengers, and mayalso severely damage the motor, pump, or valves before informationconcerning the malfunction can be transmitted to a person who can stopthe -pump drive.

In accordance with the present invention, the elevator control circuitincludes a protective timer which is started each time the motor and thepump start. The

timer is set to continue operating for the full time necessary for theelevator to make a single full trip from the bottom terminal to the topterminal without intermediate stops, plus a short additional time toaiford a safety factor. The safety factor may be only a few seconds. Thetimer runs only when the motor and pump run, .and reeycles each time thepump motor starts.

The system includes a contactor relay which closes to start the pumpmotor .and which remains closed as long as the pump motor and pump arein operation. I-f the up contactor relay remains closed for a timelonger than the predetermined time on the protective timer, the timercontacts operate to complete a safety circuit which stops the pump motorand operates the elevator control valves to return the elevator car tothe bottom terminal. When the car reaches the bottom terminal it parkswith its door open, and at the same time the protected service, or fusedswitch which controls the entire electrical control system isautomatically opened tothrow the car out of service.

At the same time that the protective circuit stops the motor and opensthe down travel valve it drops out of the control circuit the servicecircuit that includes the car and hall call registering pushbuttons, andthe indicator circuit which shows the position and direction of travelof the elevator car. Thus, the car expresses to the bottom terminalwithout stopping to answer lany calls for service, and the position anddirection indicator at the bottom terminal which would normally indicateto prospective passengers that the car is ready to travel up, are alsodisabled.

The control System is illustrated diagrammatically in the accompanyingdrawing in which those portions of the control system which are old andknown in the art .are illustrated only by appropriately labeled blocks.Thus, for example, the up hall call registration-momory-and cancellingcircuits 10 include a pushbutton service call switch on the bottomterminal floor and each ioor below the top terminal floor, .and all thenecessary relays or equivalent elements for registering the presence ofthe up call on the controller, retaining the call for service until thecar stops during upward travel to answer the call for service, and forcancelling the service call after the car has stopped. Such circuitry isvery old and well known to those skilled in the elevator art, .and isbasic to all elevator systems whether electric or hydraulic.

Similarly, the car call-registration-memory-andeconcelling circuits 12provide all the conventional controls which are required to register acall for service to a particular floor by a passenger entering the car,hold the call for service until the car stops at the desired iioor, andcancel the call.

Likewise, the down hall call-registrtion-memory-andcancelling circuits14 include the components similar to those in the up hall call circuitsexcept, of course, that there is a down call switch at the top terminaland none .at the bottom terminal except in those buildings having abasement served by the elevator.

Elevator position and direction determining circuits 16 are alsoentirely old and well known, and may include the lantern for each vloorwhich is illuminated to indicate the approach of .a car in a particulardirection of travel when a passenger on the oor has registered a callfor service in that direction by pressing a hall call button, and thedirection lanterns at the terminal oors which, when a car is parked,indicate the availability of the car for travel in the indicateddirection.

Likewise, the door operator pilot relay and timer circuits 18 includethe customary components which prevent the door from being opened untilthe elevator is stopped at a floor, the .controls which cause the dooroperator motor 20 to start opening the door the moment4 the car isstopped at the door, the timer which causes the door to remain open foronly a predetermined length of time after which it closes automatically,and the safetyl where it would be dangerous for the door to close andthe car to start.

The circuit shown in the drawing is illustrated in an across-the-lineform of diagram. No key is given for the relays and associated contactsas the drawing is relatively simple, all on one sheet, and therelationship of the contacts and relays is believed readily apparent.

The control circuit is energized from a suitable source, as 110 voltalternating current, through a protected or fused master or serviceswitch 22. One side of the source is connected with line 23 and theother with line 24. Hydraulic pump motor 25 is connected across the linethrough normally open contacts U associated with up contactor relay U.The down valve solenoid is connected across the line through normallyopen contacts D yassociated with down contactor relay D. Door operatormotor 20, which is reversible in operation, is connected for operationto open the car doors through contacts O associaated with open relay Oand to close the doors through conta-cts C associated with door closerelay C.

Specific circuitry for registering car calls is illustrated in the carcall registration-memory and cancelling circuits 12. The elevator car isprovided with a series of pushbuttons as PB-N and PB-l representing eachof the floors the car serves. The designation PB-N represents all of thefloors other than the lower terminal iioor. On closure of pushbuttonPB-N, a circuit is completed energizing car call relay NC in turnclosing contacts NC-1 and NC-2. Contact NC-ll completes a holdingcircuit for the relay while Contact NC-2 provides information to theelevator direction determining circuit 16 to establish the necessarymovement of the elevator to answer the car call. The car call circuitryfor the other oors operates in the same manner.

The up direction relay U is energized at the'time it is desired to causethe car to leave from a oor in the up direction, as a car leaves thelower terminal in response to a call car or a hall call from an upperfloor. After the doors are closed, relay U is energized closing contactU and starting the pump motor to deliver hydraulic fluid to the ram andlift the car. In accordance with the invention, the timer PT isconnected in parallel with relay U and is energized at the same time.The contacts associated with timer PT are shown in the condition theyhave before the timer has timed out. When the timer times out each ofthe PT contacts is reversed in condition. The time of timer PT is set tobe slightly longer than the time required for the elevator to travelfrom the lowest floor to the highest oor without intermediate stops. Ateach stop the pump motor is deenergized, and since PT is in parallelwith U, the timer is also deenergized. When the up direction relay U isenergized for the next up travel of the car, the timer PT is alsoenergized and again starts its cycle; and this occurs whether the car isat the bottom terminal or an intermediate floor. Thus, whether the carparks at a floor or reverses its travel, the energization circuit forrelay PT is broken and the timer resets automatically, assuming it hasnot yet reached the end of its timing period.

If the timer PT times out before the car reaches its destination and thepump stops, the safety circuitry is placed in operation. This may occurthrough a malfunction or failure of a. portion of the elevator system.The contacts associated with timer PT affect the operation of severalportions of the circuit. Contact PT-1 times closed, completing a holdingcircuit for the timer. Contact PT-S opens breaking the energizationcircuit .for up direction relay U. Contact PT-Z times open breaking theenergization circuit for the up and down hall call circuits and 14 andaffecting a portion of the call car circuitry, as will appear.

The circuitry representing a first floor car call is actuated by closureof contact PT-4 connnected in parallel with PBA. The resulting closureof contact lC-Z acts through the direction determining circuitry toenergize down direction relay D. This in turn energizes the downsolenoid valve and causes the hydraulic fluid in the cylinder to bleedslowly therefrom to lower the elevator. The elevator is caused toby-pass all other hall calls as the car call circuitry for floors otherthan the first Hoor are connected with line 23 through contact PT-2which opens on timing out of the timer PT.

When the car nears the lower terminal, a zone switch is actuated closingcontacts 1Z-2 in parallel with contacts PT-S. Contacts O associated withrelay O close, energizing door operator motor 20 to open the car doorspermitting the passengers to leave. It is necessary that the car doorsbe prevented from reclosing in this direction of the system. ContactslZ-ll open in the circuit of door close relay C. Timer contacts PT-G,parallel with contact lZ-l are also opened, and relay C cannot beenergized regardless of the actuation of other circuitry associated withthe door operator pilot relay and timer.

Timer PT is maintained in its condition through holding contact PT-l. Itcannot be reset until the protected service switch 22 is opened,breaking the power circuit for the entire system. The switch isaccessible only to authorized service personnel who, before the car isreturned to operation, can remedy the fault in the System which causedthe actuation of the protective timer. When switch 1-2 is opened, relayPT is deenergized and all of the con- -tacts associated therewith arereturned to the positions illustrated in the drawings. The timer isreset upon deenergization, as described above.

The foregoing detailed description is given for clearness ofunderstanding only and no unnecessary limitations should be understoodtherefrom, as modifications will be obvious to those skilled in the art.

I claim:

1. In a hydraulic elevator system that has a ram and an elevator car onthe ram serving a plurality of floors that include a bottom terminal anda top terminal, an electric motor driven pump to deliver fluid underpressure from a reservoir to the ram, and valve means to control flow offluid between the pump and ram to raise and lower the ram .and stop thecar at the fioors served by it, electric control means comprising: callmeans operable to register calls for service in an up direction; meansresponsive to operation of the call means for starting the electric pumpmotor and operating the valve means to raise the ram; timing means whichtimes out after a time that is somewhat in excess of the maximum timerequired to move the car from the bottom terminal to the top terminal;and means responsive to the timing out of said timing means for stoppingthe electric pump motor and actuating the valve means to lower the ramand move the car to the bottom terminal.

2. The control means of claim 1 which includes indicator circuit meansfor indicating the position and direction of travel of the car, andmeans responsive to timing out of the timing means for dropping theindicator circuit out of the control circuit.

3. The control means of claim 1 which includes service circuit meanshaving call registering means at floors served by the elevator and inthe elevator car for registering calls for service, .and meansresponsive to timing out of the timing means for dropping the servicecircuit means out of the control circuit.

4. The control means of claim 1 which includes indicator electriccircuit means continuously indicating the position and direction oftravel of the car, service circuit means having call registering meansat floors served by the elevator and in the elevator car for registeringcalls for service, and means responsive to timing out of the timingmeans for dropping the service circuit means out of the control circuit.

5. The ycontrol means of claim 1 that includes a master switch, andmeans responsive to opening of the master switch for `dropping the timeractuated means out of the circuit and thereby returning the servicecircuit means and the indicator circuit means to the control circuit.

6. In a hydraulic elevator system that has a ram and an elevator car onthe ram serving a plurality of oors that include a bottom terminal floorand a top terminal floor, a door for controlling access to the car ateach oor, an electric motor `driven pump to deliver fluid under pressurefrom .a reservoir to the ram, and valve means to control ilow of fluidbetween the pump and ram to raise and lower the ram and stop the car atthe floors served by it, electric controlmeans comprising: call meansoperable to register calls for service in `an up direction; meansresponsive to operation of the up call means for closing the door,starting the electric pump motor and operating the valve means to raisethe ram; timing means which times out after a time that is somewhat inexcess of the maximum time required to move the car from the bottomterminal to the top terminal; means responsive to the timing out of saidtiming means for stopping the electric pump motor `and actuating thevalve means to lower the ram and move the car to the botto-m terminal;and means responsive to stopping of the car at the bottom terminal foropening the door at said terminal.

7. The control means of claim 6 that includes a door operating circuitresponsive to actuation of a service circuit call registering means forclosing the `door at the bottom terminal oor, and means responsive totiming out of the timer for dropping the Idoor operating circuit out ofthe control circuit.

8. The control means of claim 7 which includes indicator electriccircuit means for indicating the position and direction of travel of thecar, service circuit means having call registering means at floorsserved by the elevator .and in the elevator car for registering callsfor service, and means responsive to timing out `of the timing means fordropping the service circuit means out of the control circuit.

9. The control means of claim 8 that includes a master switch, and meansresponsive to opening of the master switch for dropping the timeractuated means out of the circuit and thereby returning the servicecircuit means and the indicator circuit means to the control circuit.

References Cited UNITED STATES PATENTS 2,647,590 7/1953 Anderson 187-292,695,077 11/1954 Suozzo 187-29 ORIS L. RADER, Primary Examiner.

T. LYNCH, Assistant Examiner.

